This invention relates to combustors, and more particularly to combustor liners and heat shield panels for gas turbine engines.
Gas turbine engine combustors may take several forms. An exemplary class of combustors features an annular combustion chamber having forward/upstream inlets for fuel and air and aft/downstream outlet for directing combustion products to the turbine section of the engine. An exemplary combustor features inboard and outboard walls extending aft from a forward bulkhead in which swirlers are mounted and through which fuel nozzles/injectors are accommodated for the introduction of inlet air and fuel. Exemplary walls are double structured, having an interior heat shield and an exterior shell. The heat shield may be formed in segments, for example, with each wall featuring an array of segments two or three segments longitudinally and 8-12 segments circumferentially. To cool the heat shield segments, air is introduced through apertures in the segments from exterior to interior. The apertures may be angled with respect to longitudinal and circumferential directions to produce film cooling along the interior surface with additional desired dynamic properties. This cooling air may be introduced through a space between the heat shield panel and the shell and, in turn, may be introduced to that space through apertures in the shell. Exemplary heat shield constructions are shown in U.S. Pat. Nos. 5,435,139 and 5,758,503. Exemplary film cooling panel apertures are shown in U.S. Pat. No. 6,606,861.
U.S. Pat. No. 6,255,000 discloses a laminated combustor heat shield construction known by the trademark LAMILLOY. Such construction involves multiple layers each having apertures and pedestals, the pedestals of one layer becoming bonded to the opposite surface of the next layer. The space around and between the pedestals defines a series of plenums vented by the apertures. Nevertheless, there remains room for improvement in heat shield technology.